The present invention relates to a substrate treating method and apparatus for subjecting a semiconductor substrate to a required treatment, more specifically to a substrate treating method and apparatus which can perform in-situ monitoring of surface states of a semiconductor substrate at a fabrication site and, based on results of the in-situ monitoring, can control treating conditions or detect the end point of the treatment.
Recently, semiconductor devices have elements increasingly micronized, and are made increasingly three dimensional. This makes it difficult for cleaning solutions to intrude into micronized regions or steep steps or to be replaced there. In consideration of future further micronization, dry cleaning, which uses no chemical liquid is noted.
The dry cleaning is art that radiation, e.g., UV radiation for decomposing or dissociating contaminants is applied to a semiconductor substrate, or active species are introduced while the UV radiation is being applied to thereby decompose and remove the contaminants adhered to the semiconductor substrate. For example, to remove organic contaminants staying on silicon substrates reaction with ozone or oxygen excited by UV radiation is effective. Oxygen molecules are dissociated to oxygen atoms by light of a below 242 nm wavelength. The organic contaminants are oxidized by the oxygen atoms and decomposed into H2O, O2, CO, Co2, etc. of high vapor pressures. Organic bonds, such as Cxe2x80x94C, Cxe2x80x94H, Cxe2x80x94O, etc. can be dissociated by the UV radiation. Thus, the contaminants on the semiconductor substrate can be removed.
Thus, knowing surface states of semiconductor substrates is very important also to control parameters for the dry cleaning, such as an optimum irradiation intensity, wavelength, oxygen amount, etc. Accordingly, a dry cleaning method and apparatus which enable in-situ monitoring of surface states of a semiconductor substrate at the fabrication site and control of operation parameters based on results of the in-situ monitoring are required.
On the other hand, plasma etching technique is widely used in patterning steps for forming device structures on semiconductor substrates. Recently, semiconductor devices have elements increasingly micronized, and are made increasingly three dimensional. This makes it difficult for cleaning solutions to intrude into micronized regions or steep steps or to be replaced there. Under these circumstances, dry cleaning using plasma etching is noted as a cleaning method using no chemical solutions.
Here, the plasma etching is dry etching using reactive gas plasmas and removes substances-to-be-treated mainly by actions of neutral active species.
The plasma etching process is determined by dynamic balance in adsorption, reaction and elimination processes between influxes of radical ions, etc. fed in gas phase and outfluxes from semiconductor substrate surfaces. In the plasma etching process, to set optimum plasma etching conditions and to detect the end point of the plasma etching, it is very effective to know adsorption states, chemical bonding states, structures and thicknesses of reaction layers, etc. of surface states of semiconductor substrates. Accordingly, a plasma etching method and apparatus which enable in-situ monitoring of surface states of a semiconductor substrate at the fabrication site and control of operation parameters based on results of the in-situ monitoring are required.
Thus, knowing surface states of semiconductor substrates is required not only in the dry cleaning and the plasma etching but also in other various sites. Various monitoring methods have been conventionally proposed, and some have been practiced.
Means for monitoring a surface state of a semiconductor substrate by internal multiple reflection of infrared radiation is provided by, e.g., FT-IR (Fourier-transform spectroscopy) apparatus or the special use marketed by Perkin-Elmer Co., U.S.A. For wider applications of the means Graseby Specac Limited, for example, markets various accessories.
In the conventional surface state monitoring method using this means, as exemplified in FIG. 11A, a substrate-to-be-treated 102 is cut into, e.g., a 40 mmxc3x9710 mm strip, and infrared radiation emitted from an infrared radiation source 104 is passed through the substrate-to-be-treated 102 to monitor states of the substrate surfaces. Otherwise, as exemplified in FIG. 11B, a substrate-to-be-treated 102 has the end tapered, and infrared radiation is incident on the end surface of the substrate-to-be-treated 102 to undergo multiple reflection inside the substrate, whereby a surface state of the substrate is monitored. Otherwise, as exemplified in FIG. 1C, infrared radiation is incident on a substrate-to-be-treated via a prism 106 positioned above the substrate to undergo multiple reflection inside the substrate, whereby a surface state of the substrate is monitored.
However, these monitoring methods needs cutting a substrate-to-be-treated into strips, additionally processing the substrate-to-be-treated, or disposing a prism above a substrate-to-be-treated. These monitoring methods have not been usable in the in-situ monitoring at site of fabricating semiconductor devices.
Methods of monitoring organic contaminants on semiconductor substrates are known, such as thermal desorption GC/MS (Gas Chromatography/Mass Spectroscopy), APIMS (Atmospheric Pressure Ionization Mass Spectroscopy), TDS (Thermal Desorption Spectroscopy), etc. However, these methods are not suitable to be used in-situ monitoring at site of fabricating semiconductor devices for reasons that these methods cannot directly observe large wafers of, e.g., above 300 mm-diameters which are expected to be developed, and need vacuum ambient atmosphere, and have low throughputs, and other reasons.
As described above, the above-described conventional monitoring methods, which are destructive, are not usable in the in-situ monitoring at site of fabricating semiconductor devices or are not suitable for monitoring large semiconductor wafers. These method are unapplicable not only to the in-situ monitoring of surface states of a semiconductor substrate for controlling operation parameters for the dry cleaning, but also to the in-situ monitoring of surface states of a semiconductor substrate for controlling operation parameters for the plasma etching.
The apparatuses for the above-described conventional dry cleaning and plasma etching includes no suitable means for confirming whether or not each substrate has reached prescribed values in actual steps, so that the dry cleaning and plasma etching are completed after set periods of time or whether all substrates have reached prescribed values. Accordingly, the treatments are not sufficient, and residues are generated, or excessive treatments are performed, damaging the substrates. The excessive treatments are not preferable in view of throughputs.
An object of the present invention is to provide a substrate treating method and apparatus which enable the in-situ monitoring of surfaces states of a semiconductor substrate at the fabrication site and the control operation parameters based on results of the monitoring, and can detect the end point of the treatment.
The above-described object is achieved by a substrate treating apparatus comprising: a substrate treating means for subjecting a substrate-to-be-treated to a required treatment; a surface state monitoring means including an infrared radiation condensing means for condensing infrared radiation or near-infrared radiation emitted by an infrared radiation source onto an outer peripheral part of the substrate-to-be-treated, an infrared radiation detecting means for detecting the infrared radiation or near-infrared radiation which has undergone multiple reflection inside the substrate-to-be-treated and exited from the substrate-to-be-treated, and an infrared radiation analyzing means for analyzing the infrared radiation or near-infrared radiation detected by the infrared radiation detecting means, the surface state monitoring means monitoring in-situ a surface state of the substrate-to-be-monitored when the substrate-to-be-treated is treated by the substrate treating means; and a control means for controlling the substrate treating means, based on the surface state of the substrate-to-be-treated, which was monitored by the surface state monitoring means. A substrate-to-be-treated can have the surface monitored uncontiguously and non-destructively without being deformed or damaged, being subjected to extra chemical etching, processing of the end surface, etc. or introducing infrared radiation or near-infrared radiation through optical members, such as prisms positioned above the substrate-to-be-treated. Accordingly, surface states of a substrate-to-be-treated are in-situ monitored at site of the fabrication, and operation parameters are controlled based on results of the surface state monitoring, so that the substrate-to-be-treated can be treated always under optimum conditions.
In the above-described substrate treating apparatus, it is possible that the infrared radiation analyzing means monitors the surface state of the substrate-to-be-treated, based on a spectroscopic results given by Fourier transform spectroscopy.
In the above-described substrate treating apparatus, it is possible that the infrared radiation analyzing means monitors the surface state of the substrate-to-be-treated, based on a spectroscopic result given by infrared spectroscopy using a diffraction lattice.
In the above-described substrate treating apparatus, it is possible that the substrate treating means is a cleaning means for decomposing and removing a contaminant adhered to the substrate-to-be-treated by light irradiation, the surface state monitoring means monitors a kind and/or an amount of the contaminant adhered to the substrate-to-be-treated, and the control means controls treating conditions for treating the substrate-to-be-treated by the cleaning means, based on the kind and/or the amount of the contaminant given by the surface state monitoring means.
In the above-described substrate treating apparatus, it is possible that the control means controls an irradiation intensity or an irradiation period of time of the light to be irradiated to the substrate-to-be-treated, based on the kind and/or the amount of the contaminant given by the surface state monitoring means.
In the above-described substrate treating apparatus, it is possible that the cleaning means includes an active species supply means for supplying an active species which reacts with the contaminant.
In the above-described substrate treating apparatus, it is possible that the control means controls a supply amount of the active species to be supplied by the active species supply means, based on the kind and/or the amount of the contaminant given by the surface state monitoring means.
In the above-described substrate treating apparatus, it is possible that the apparatus further comprises an end point detecting means for detecting an end point of the substrate treatment, based on the kind and/or the amount of the contaminant given by the surface state monitoring means.
In the above-described substrate treating apparatus, it is possible that the end point detecting means judges whether or not the substrate-to-be-treated has arrived at the end point by comparing a monitored level of resonance absorption intensity of the infrared radiation or near-infrared radiation of the contaminant with a prescribed reference level.
In the above-described substrate treating apparatus, it is possible that the substrate treating means is an etching means for etching the substrate-to-be-treated by using a plasma; and the control means controls etching conditions for etching the substrate-to-be-treated by the etching means, based on the surface state of the substrate-to-be-treated monitored by the surface state monitoring means.
In the above-described substrate treating apparatus, it is possible that the control means controls a state of the plasma, based on the surface state of the substrate-to-be-treated monitored by the surface state monitoring means.
In the above-described substrate treating apparatus, it is possible that the surface state monitoring means monitors an adsorption state of an influx or an outflux, a chemical bonding state or a structure of a reactive layer on the surface of the substrate-to-be-treated.
In the above-described substrate treating apparatus, it is possible that the surface state monitoring means monitors a kind and/or an amount of a contaminant adhered to the surface of the substrate-to-be-treated.
In the above-described substrate treating apparatus, it is possible that the apparatus further comprises an end point detecting means for detecting an end point of the etching, based on the surface state of the substrate-to-be-treated monitored by the surface state monitoring means.
In the above-described substrate treating apparatus, it is possible that the control means stops the treatment of the substrate-to-be-treated, based on end point information given by the end point detecting means.
In the above-described substrate treating apparatus, it is possible that the substrate-to-be-treated has a declined part on the outer peripheral part, which is formed by chamfering the corner defined by the surface of the substrate-to-be-treated and an outer peripheral surface thereof; the infrared radiation condensing means condenses the infrared radiation or near-infrared radiation onto the declined part of the substrate-to-be-treated.
In the above-described substrate treating apparatus, it is possible that the infrared radiation condensing means condenses the infrared radiation or near-infrared radiation into a circular or an empirical focus.
In the above-described substrate treating apparatus, it is possible that the infrared radiation source is an explosion-proof type infrared radiation source having a light source for emitting the infrared radiation or near-infrared radiation sealed in a vessel.
The above-described object is also achieved by a substrate treating method for subjecting a substrate-to-be-treated to a required treatment comprising: condensing infrared radiation or near-infrared radiation onto an outer peripheral part of a substrate-to-be-treated before treating the substrate-to-be-treated or in treating the substrate-to-be-treated and introducing the infrared radiation or near-infrared radiation; detecting the infrared radiation or near-infrared radiation which has undergone multiple reflection in the substrate-to-be-treated and exited from the substrate-to-be-treated; analyzing the detected infrared radiation or near-infrared radiation to monitor a surface state of the substrate-to-be-treated; and controlling treating conditions for treating the substrate-to-be-treated by the required treatment in accordance with the monitored surface state of the substrate-to-be-treated.
The above-described object is also achieved by a substrate treating method for subjecting a substrate-to-be-treated to a required treatment comprising: condensing infrared radiation or near-infrared radiation onto an outer peripheral part of a substrate-to-be-treated in treating the substrate-to-be-treated and introducing the infrared radiation or near-infrared radiation; detecting the infrared radiation or near-infrared radiation which has undergone multiple reflection in the substrate-to-be-treated and exited from the substrate-to-be-treated; analyzing the detected infrared radiation or near-infrared radiation to monitor a surface state of the substrate-to-be-treated; and detecting an end point of the required treatment of the substrate-to-be-treated, based on the monitored surface state of the substrate-to-be-treated.
An end point of a treatment of a substrate-to-be-treated can be detected based on results of the surface state monitoring. A device being fabricated on the substrate-to-be-treated can be protected from damage. The substrate can be advanced to next processing without being excessively treated, and higher throughputs can be obtained. The treatment can have uniform quality.
In the above-described substrate treating method, it is possible that a monitored level of resonance absorption intensity of the infrared radiation or near-infrared radiation is compared with a prescribed reference level to judge whether or not the required treatment has reached the end point.
In the above-described substrate treating method, it is possible that the required treatment is for decomposing and removing a contaminant adhered to the substrate-to-be-treated by light irradiation; and in monitoring the surface state of the substrate-to-be-treated the contaminant adhered to the surface of the substrate-to-be-treated is monitored, and treatment conditions for the cleaning treatment are controlled in accordance with a monitored kind and/or amount of the contaminant.
In the above-described substrate treating method, it is possible that in the step of cleaning the substrate-to-be-treated, an active species reactive with the contaminant is supplied.
In the above-described substrate treating method, it is possible that a supply amount of the active species is controlled based on the surface state of the substrate-to-be-treated.
In the above-described substrate treating method, it is possible that an irradiation intensity or an irradiation period of time of the light to be irradiated to the substrate-to-be-treated is controlled based on the surface state of the substrate-to-be-treated.
In the above-described substrate treating method, it is possible that the required treatment is for etching the substrate-to-be-treated using a plasma, and conditions for the etching are controlled based on the monitored surface state of the substrate-to-be-treated.
In the above-described substrate treating method, it is possible that a state of the plasma is controlled based on the monitored surface state of the substrate-to-be-treated.
In the above-described substrate treating method, it is possible that the etching conditions are determined based on results of monitoring an adsorption state of an influx or an outflux, chemical bonding states or structures of reactive layers on the surface of the substrate-to-be-treated.
In the above-described substrate treating method, it is possible that the etching conditions are determined based on monitored results of a kind and/or an amount of the contaminant adhered to the surface of the substrate-to-be-treated.
In the above-described substrate treating method, it is possible that the infrared radiation or near-infrared radiation is incident on a declined part on the outer peripheral part of the substrate-to-be-treated, which is formed by chamfering the corner defined by the surface of the substrate-to-be-treated and an outer peripheral surface thereof and is introduced from the declined part into the substrate-to-be-treated.
In the above-described substrate treating method, it is possible that the infrared radiation or near-infrared radiation exited from the substrate-to-be-treated is spectroscoped by Fourier transform spectroscopy, and the contaminant is monitored based on a result of the spectroscopy.
In the above-described substrate treating method, it is possible that the infrared radiation or near-infrared radiation exited from the substrate-to-be-treated is spectroscoped by a diffraction lattice, and the contaminant is monitored based on a result of the spectroscopy.
In the above-described substrate treating method, it is possible that the monitoring is repeated plural times while the substrate-to-be-treated is being rotated to monitor the surface state of the substrate-to-be-treated substantially all over the surface of the substrate-to-be-treated, and the treating conditions of the substrate-to-be-treated are controlled based on the monitored surface state of the substrate-to-be-treated.